Remove or Delete monitor display preferences as defined by the User -

I believe the plist for display preferences are in:

users > YourName > Library > Preferences > ByHost > com.apple.preference.displays.\[long number].plist

The instructions Antonio gives you are if you want to remove pretty much all preferences for a user. Since I have over 300 preferences files I wouldn't want to do that!

DearJane

Create a folder on the Desktop. Call it whatever you like. Navigate to /Users/Home/Library/Preferences. Select everything in there. De-select com.apple.mail.plist and com.apple.dock.plist. The rest of the selected files move them to the previously created folder on the desktop.

Restart your mac

HTH?

Tony

DearJane

As Limnos points out my suggestion takes a rather blanket approach which may not suit you? However it's also fair to say that problems potentially caused due to damaged and/or corrupted .plists are not exclusive to a single .plist. Occasionally its a combination of 2, 3 or 4 or possibly more that causes the problem.

Hence my suggestion to create a folder on the desktop first. That way if the problem goes away you can introduce desired .plist files later on once you test everything else. It's also my experience that most mac users can benefit from having a major clearout. Couple this with clearing out the contents of /Users/Home/Library/Caches and overall performance can seem quite marked.

A lot does depend on how many 3rd-Party applications/utilities you've added. I have lots of added extras and it does not cause me any problems whenever I clear them all out.

The choice is yours.

HTH?

Tony